The present invention relates to a semiconductor device and a technique of manufacturing the same, particularly, to a through silicon via (TSV) technique that is required in manufacturing three-dimensional multifunctional devices in which heterogeneous devices are stacked vertically such as memory devices, a memory device and a logic device, or a micro electro mechanical system (MEMS).
Until now, in the manufacturing of semiconductor elements, a fine processing technology using photolithography has been used. However, presently, design dimensions of semiconductor elements become shorter than wavelengths of light to be used in the photolithography, and miniaturization of semiconductor elements by the photolithography approaches the limits. Therefore, in order to further improve the performance of semiconductor elements, a three-dimensional wiring technique, in which semiconductor chips are stacked vertically, attracts attention as a so-called “More Than Moore” technique.
Incidentally, as one of the most important techniques for realizing three-dimensional wiring, there is the TSV technique. The TSV technique is a technique of forming a through electrode passing through a silicon substrate vertically in a thickness direction. In the TSV technique, depending on timing for forming the through electrode, there are three systems: (1) a via first system (TSV is formed before forming semiconductor devices), (2) a via middle system (TSV is formed in the formation process of semiconductor devices), and (3) a via last system (TSV is formed after forming semiconductor devices).
Among these, since the via last system is easy to be introduced into the manufacturing process of a semiconductor device as compared with other systems, investigations into the practical application of the TSV technique by the via last system is actively performed. For example, a TSV technique by the via last system is described in Non-patent document 1 (P. Leduc, et al., “First integration of Cu TSV using die-to-wafer direct bonding and planarization,” IEEE 3D System Integration Conference 2009).